Metal–Thiobenzoato Complexes: Synthesis, Structure, and Processing as Carbon-Supported Nanoparticles

Article abstract of DOI:10.1002/ejic.201701475

Six new compounds of formula [M(TBn)₂L] [TBn: thiobenzoato; M: Pd^II, Zn^II, Cd^II; L: 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 1,2-di-(4-pyridil)-ethylene (bpe), neocuproine (neo), adenine (ade)] are obt

Full text of DOI:10.1002/ejic.201701475

A Journal of
Accepted Article
Title: Metal-Thiobenzoato Complexes: Synthesis, Structure and
Processing as Carbon Supported Nanoparticles
Authors: Daniel Vallejo-Sánchez, Garikoitz Beobide, Oscar Castillo,
Monica Lanchas, Antonio Luque, Sonia Pérez-Yáñez, and
Pascual Roman
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content of this Accepted Article.
To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201701475
Link to VoR: http://dx.doi.org/10.1002/ejic.201701475

10.1002/ejic.201701475
European Journal of Inorganic Chemistry
FULL PAPER
7DOI: 10.1002/ejic.201((will be filled in by the editorial staff))
Metal-Thiobenzoato Complexes: Synthesis, Structure and Processing as Carbon
Supported Nanoparticles
Daniel Vallejo-Sánchez,[a] Garikoitz Beobide,*[a] Oscar Castillo,*[a] Mónica Lanchas,[a] Antonio
Luque,[a] Sonia Pérez-Yáñez,[a, b] Pascual Román[a]
Keywords: thiobenzoato / thiocarboxylato / single-source precursors / carbon supported nanoparticles / dry thermolysis
Six new compounds of formula [M(TBn)2L] [TBn: thiobenzoato; The presence of direct sulfur-metal bonds and carbon rich co-
M: Pd(II), Zn(II), Cd(II); L: 2,2’-bipyridine (bpy), 1,10- ligands enabled these complexes to yield by means of a dry
phenanthroline
(phen),
1,2-di-(4-pyridil)-ethylene
(bpe), thermolysis process a set of metallic and metal sulfide
neocuproine (neo), adenine (ade)] were obtained by the reaction of nanoparticles embedded into a carbonaceous support. The
M(CH3COO)2·2H2O with thiobenzoic acid and N-heterocyclic process to produce the latter materials consisted in an aerobic
ligands. The use of chelating ligands and adenine led to thermolysis using moderate temperatures (300–500ºC) and short
monomeric
compounds:
[Pd(TBn)2(bpy)]
(PdBPY), exposure times (minute scale). The analysis of the XRD patterns
[Pd(TBn)2(phen)] (PdPHEN), [Zn(TBn)2(neo)] (ZnNEO), and SEM/TEM images reveal that the carbonaceous matrix hosts
[Cd(TBn)2(neo)] (CdNEO), and [Cd(TBn)2(ade)(CH3OH)] well dispersed nanocrystallites. The influence of the M(II) atom,
(CdADE). In these compounds the metal is bonded to sulfur atoms ancillary ligand and thermal treatment parameters on the
of two Tbn anions while the remaining coordination positions are crystalline phase, size and purity of the resulting carbon
completed by the donor atoms of the ancillary ligands. The supported nanoparticles is discussed.
bridging capability of the bpe ligand gave rise to the polymeric
[Cd(TBn)2(μ–bpe)]n (CdBPE) compound.
____________
works,[5] as it allows to prepare nanostructures by using solely
[a]
Departamento de Química Inorgánica, Facultad de Ciencia y
Tecnología, Universidad del País Vasco (UPV/EHU), Apartado 644,
E–48080 Bilbao, Spain
metal-organic precursors. In comparison to solvent assisted single-
source precursor route, dry thermolysis implies lower costs as
diminishes the use of toxic and environmentally unfriendly organic
solvents and hardly extractable surfactants. In this solventless
approach, during the heating process the ligands passivate the
surface of the particle limiting its growth, and as consequence,
determine its size. The nature of the ligand influences also on the
final phase and crystallinity of the achieved metal chalcogenide.[6]
In general, during the thermolysis of the precursor, moderate
temperatures are used to prevent the sintering of the NPs, but it also
implies a generally quite high percentage of carbon impurities
because of the lack of sufficient energy to complete the elimination
of the ligands.[7]
Fax: 34-94601-3500
E-mail: garikoitz.beobide@ehu.eus, oscar.castillo@ehu.eus.
https://www.ehu.eus/en/web/dqi/
[b] Departamento de Química Inorgánica, Facultad de Farmacia,
Universidad del País Vasco (UPV/EHU), E–01006 Vitoria-Gasteiz,
Spain
Introduction
Thiocarboxylato ligands provide a valuable tool to design and
synthesise metal-complexes as the presence of both soft sulfur and
hard oxygen donor sites implies not only the ability to bind metals
of rather different nature,[1] but it also endorses appealing
electronic properties such as luminescence and conductivity.[2]
Apart from that, complexes of chalcogenide have been studied as
precursors for the deposition of II/VI type semiconductor
nanoparticles through single-source precursor routes,[3] which
makes this kind of coordination compounds of particular interest
due to the increasing demand of quantum dots (QDs) for
technological applications.[4] Precisely, the single-source precursor
routes employ sulfur containing coordination compounds as
starting material since metal-chalcogenide bonds are already
present in the structure. In this approach, the metal-organic
precursor is dispersed in a coordinating solvent (usually amines or
amides) and injected into a hot solution containing a surfactant in
order to stabilize the chalcogenide particles and to limit their
growth. Thus, nanoparticles (NPs) with narrow size distributions
are achievable. More recently, an alternative procedure called
solventless thermolysis have been the focus of several research
Although in a first instance the non-volatilized carbonaceous
part could be considered a disadvantage, numerous studies prove
that heterostructures based on semiconducting nanoparticles
embedded in carbon materials show promising features for its
implementation in batteries, electrocatalysis and photocatalysis.[8]
In fact, the dispersion of metal nanoparticles on a carbon matrix is
a common practice in industry since this class of hybrid materials
are widely employed as electrochemical electrodes for fuel cell[9]
and battery applications,[10] as well as heterogeneous catalyst for
organic
synthesis,[11]
hydrodesulfurization,[12]
wastewater
treatment,[13] etc. Furthermore, the carbon matrix prevents the
agglomeration and sintering of the nanoparticles and in the same
way it serves as continuous, porous and conductive support.
Conventional methods for the preparation of heterogeneous
catalysts focus on impregnation or dip-coating techniques that
require long optimization times to achieve reproducible and
1
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10.1002/ejic.201701475
European Journal of Inorganic Chemistry
FULL PAPER
homogeneous results.[14] The controlled decomposition of metal-
organic precursors in solid state opens a novel synthetic single-
stage route for the production of carbon-based nanocomposites
implying benefits related to solvent dispensal, technical simplicity,
and lower manufacturing cost.
range from 4 to 6. Initially, ruling out the semicoordination of
oxygen atoms, the coordination polyhedron (MN2S2) of ZnNEO,
CdBPE, CdNEO and CdADE can be described as a distorted
tetrahedron. The small ionic radius of ZnII imposes great steric
hindrances that implies long Zn···O contacts (3.06 Å) and results
into a coordination environment notably closer to the ideal
tetrahedral geometry. On the other hand, the bigger CdII size allows
to set shorter Cd···O contacts (2.55–2.85 Å) and it leads to small
deviation respect to polyhedrons of greater coordination numbers.
In a previous work[15] we demonstrated that thiocarboxylato
complexes can be employed as single-source precursors for the
synthesis of zinc sulfide nanoparticles. It was concluded that dry
thermolysis, under aerobic conditions, of thioacetato complexes
favoured the formation of highly pure sulfides. In this work we are
focused on replacing the thioacetato ligand by the more stable
thiobenzoato ligand in combination with N-heterocycle ligands of
Table 1. Continuous shape measures (CShM) calculation
results.[16]
Compound
Geometries [a]
C.N. = 5
TBPY SPY
different C/N ratio and aromaticity degree to provide
a
C.N. = 4
SP
C.N. = 6
carbonaceous matrix for the resulting nanoparticles. In particular,
six new MII (Pd, Cd, and Zn) thiobenzoate compounds containing
N-donor ligands (phen, neo, bpy, bpe and ade) were prepared and
structurally characterized, after which they were subjected to dry
thermolysis under aerobic conditions and moderate temperatures to
provide Pd/C, ZnS/C and CdS/C composites.
T
OC
—
—
TPR
—
—
PdBPY
PdPHEN
ZnNEO
CdBPE
CdNEO
CdADE
0.70 30.73
0.81 28.56
29.12 2.80
26.14 2.67
29.12 5.46
28.23 2.06
—
—
8.05
2.86
3.41
3.29
—
—
8.09 25.62 13.78
7.32
6.27
6.61 11.26
8.40 12.10
3.89 11.78 4.53
[a] SP: square-planar, T: tetrahedron, TBPY: trigonal bipyramid, SPY:
square pyramid, OC: octahedron, TPR: trigonal prism.
Results and Discussion
This section describes first the crystal structures of the metal-
organic precursors, as these data will support the discussion
regarding the formation of carbonaceous composites of metal and
metal sulfide nanoparticles (M/C and MS/C, respectively). Prior to
the dry thermolysis experiments, a sub-section devoted to
preliminary thermogravimetric analyses is presented in which
decomposition mechanism and optimum treatment temperature
ranges will be set. Thereafter, results on the dry thermolysis
experiments are thoroughly discussed, detailing the microstructures
and particle sizes obtained in each case, to end up with the
influence of the thermal treatment parameters.
All compounds, except CdBPE, consist of discrete monomeric
entities in which the supramolecular assembly is strongly
determined by the interactions ocurring between TBn and the N-
donor co-ligand, as described below. Bpy and phen ligands in
compounds PdBPY and PdPHEN are able to link complex entities
through T-shaped aromatic interactions and weak C–H···O and C–
H···S hydrogen bonds. On the contrary, the more extended neo
ligand in compound ZnNEO establishes π-π parallel stacking
interactions that assisted by C–H···O hydrogen bonds assemble the
monomeric entities into 1D supramolecular chains. The neo ligand
in compound CdNEO, establishes again π-π parallel stacking
interactions between them to arrange monomeric entities into
supramolecular dimers that are held together by means of T-shaped
aromatic interactions and weak C–H···O and C–H···S hydrogen
bonds. The presence of the bridging bpe ligand in compound
CdBPE, affords a zig-zag 1D polymeric complex entity with
Cd···Cd distances of 14.057 and 13.851 Å. These chains are held
together by means of T-shaped aromatic interactions among the
benzene aromatic rings and weak C–H···O and C–H···S hydrogen
bonds. In compound CdADE, the adenine molecule is coordinated
to the cadmium atom through its N7 donor position. This
coordination mode is reinforced by an additional intramolecular
hydrogen bond between the N6–H amino group and the oxygen
atom of the coordinated methanol molecule. Further details on the
crystal structures, including packing views and bond distances, are
gathered in the supporting information.
Crystal structure of precursors. At first glance, the
coordination sphere of these complexes (Figures 1 and 2) involves
two sulfur bonded thiobenzoate ligands and the remaining
coordination positions are occupied by two nitrogen donor atoms
from a chelating N,N´-heterocyclic ligand in compounds PdBPY,
PdPHEN, ZnNEO and CdNEO and from two N,N´-pillared
bridging ligands in compound CdBPE. In the case of CdADE,
apart from the two S atoms, the coordination sphere is completed
by a nitrogen atom from an adenine molecule and the oxygen atom
of a methanol molecule. At deeper insight, coordination sphere and
corresponding polyhedron can be affected by the semicoordination
of thiocarboxylate O atoms which is dependent of the metal type
and size as well as the bulkiness of the co-ligands of each
compound. As expected from its electronic configuration, PdII (d8)
does not present such semicoordination (Pd···O: 3.32–3.39 Å;
distances larger than the sum of the van der Waals radii) and it sets
in all cases a square planar coordination geometry [S(sp)=0.70–
0.81] (Table 1). On the contrary, the semicoordination of O atoms
in ZnII and CdII (d10) complexes leads to coordination numbers that
2
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10.1002/ejic.201701475
European Journal of Inorganic Chemistry
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Figure 1. ORTEP diagrams of compounds (a) PdBPY, (b) PdPHEN, and (c) ZnNEO showing the labelling scheme. Hydrogen atoms are omitted for clarity.
Symmetry codes: (i) -x+1, y, -z+1/2; (ii) -x+3/2, y, -z+1; (iii) -x+1, y, -z+3/2.
Figure 2. ORTEP diagrams of compounds (a) CdBPE, (b) CdNEO, and (c) CdADE showing the labelling scheme. Hydrogen atoms are omitted for clarity.
Decomposition mechanism and optimum treatment
temperature. The evaluation of synthesized compounds as single-
source precursors for carbon supported nanomaterials was initially
checked by thermogravimetric measurements in order to define an
optimum range to afford desired products. The thermal degradation
under synthetic air atmosphere shows (Figure 3a) that all
compounds start their decomposition at relatively low temperatures
(PdBPY: 198ºC; PdPHEN: 230ºC; ZnNEO: 239ºC; CdBPE: 220ºC;
CdNEO: 237ºC; CdADE: 151ºC). Apparently, the decomposition
temperatures are more dependent on the nature of the co-ligands
than on the type of the metal centers. In fact, compounds
containing a chelating ligand with three fused aromatic hexagonal
rings (phen and neo), provide thermally more robust products
(230–240ºC) whereas the remaining compounds are notoriously
less stable. The analysis of DTA curves (Figure 3b) indicates the
occurrence of an endothermic event possibly related to a pyrolytic
partial fragmentation of the ligands. After this first mass loss all
compounds achieve a more or less stable plateau that corresponds
to a variable mixture of PdSO4 or MIIS (MII: Zn, Cd) nanoparticles
and amorphous carbon, as confirmed by PXRD and microanalysis
of these intermediates (see Table S3.1 in the supporting
information). Precursors provided with non-fused pyridine ligands
such as bpe and bpy generate samples with low carbon content (2–
4 %) as the fragments formed during the thermolysis (i.e. pyridine,
methylamine, H2O, NH3) are more volatile in nature.[17] In
precursors PdBPY and PdPHEN, the previously formed PdSO4
decomposes around 330–350 °C to form elemental palladium.
At greater temperatures, between 295 and 485ºC, there is a
second weight loss consisting of an overlapped set of exothermic
stages related to the oxidation of the carbonaceous phase.
Amorphous carbon typically burns at temperatures ranging from
550 to 610°C under aerobic conditions.[18] Nevertheless, in PdBPY
and PdPHEN a substantial lowering in the combustion temperature
is noticed implying a decrease of ca. 300ºC respect to the typical
onset temperature. This fact is explained by the catalytic activity of
palladium prompting the oxidation of soot.[19] In group 12
transition metal precursors, the metal sulfide is further oxidized to
give ZnO (JPDS: 01-075-0576; P63mc) in the case of ZnNEO or a
mixture of CdO (JPDS: 00-001-1049; Fm-3m) and cadmium
oxysulfate (JPDS: 00-032-0140; Cm2a) for CdBPE, CdNEO and
CdADE. In PdBPY and PdPHEN, at this temperature range, the
previously formed elemental palladium undergoes a passivation
with the consequent formation of a thin layer of PdO (JCPDS: 01-
075-0584; P-4n2). Additional thermoanalytic data are available in
the supporting information.
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10.1002/ejic.201701475
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Dry thermolysis experiments. The aforementioned results
indicate that by controlling the thermal decomposition process it is
possible to access metal and metal sulfides even under aerobic
conditions. It deserves to note that, as far as we are concerned, all
the dry thermolysis processes reported up to date, except our
previous work,[15] make use of an inert atmosphere in order to yield
the corresponding metal chalcogenide. Taking into account the
results of the thermogravimetric analyses, precursor powders were
introduced for 15 minutes in a tubular oven open to air and
preheated to a temperature at which intermediate sulfides or
palladium metal are expected to be formed (see Table 2).
The X-ray diffraction profiles taken on thermolysis products
prove their crystalline nature (Figure 4) and confirm the
achievement of the pursued phase. In the residues of compounds
PdBPY and PdPHEN the cubic phase of elemental palladium is
found. Additionally, in compound PdPHEN
a small peak
corresponding to the plane (110) of tetragonal PdO is glimpsed.
The resulting ZnS obtained from compound ZnNEO corresponds
to the wurtzite phase. This polymorph is metastable at standard
conditions in bulk state (the transformation from blende to wurtzite
occurs at 1020 ºC)[20] and it is more interesting than the blende
cubic phase in terms of optoelectronic properties.[21] CdS obtained
from compound CdBPE corresponds to a mixture of wurtzite and
blende polymorphs, but CdNEO and CdADE precursors render the
pure CdS wurtzite and blende phases, respectively. Thus, it can be
concluded that the correct choice of the N-donor co-ligand allows
stabilizing a specific crystalline phase.
The amount of carbon accompanying nanoparticles, ranging
from 2 to 43 %wt, depends on the starting material, being notorious
the presence of a greater percentage of carbon in compounds
containing molecules with fused aromatic rings as ancillary ligand
(PdPHEN, ZnNEO, CdADE and CdNEO).
The average crystallite size of the as-synthesized nanoparticles
was estimated from Debye-Scherrer[22] equation (Table 2). The
great widening of diffraction peaks observed in ZnS and CdS
samples reveals the nanometric nature of the crystalline domains
for which size estimate ranges from 8 to 19 nm. In contrast, full
widths at half maximum (FWHM) of the measured signals for
metal palladium samples are markedly thinner, and lead to
crystallite size of 60–70 nm. Note that particle size obtained from
XRD analyses corresponds to the statistic of the bulk sample, and
the contribution of the smallest particles is masked. This fact will
be further discussed in TEM (transmission electron microscopy)
analyses.
Figure 3. (a) Thermogravimetric analysis of metal(II)-thiobenzoate
compounds under synthetic air atmosphere and (b) their corresponding
DTA curves.
Table 2. Main characteristics of the dry thermolysis products obtained under aerobic conditions.
Precursor
PdBPY
T (ºC)
345
Products (JPDS Card) [a]
Pd (01-087-0638)
DXRD (nm) [b]
DTEM (nm) [c]
3±1 / 119±52
C.V. (%) [d]
33.3 / 43.7
C (% wt) [e]
60
1.6
Pd (01-087-0638)
PdPHEN
ZnNEO
CdBPE
480
400
400
70
21±6 / 78±26
8±2
28.6 / 33.3
25.0
38.4
41.8
3.9
PdO (01-075-0584)
w-ZnS (00-036-1450)
c-CdS (00-042-1411)
w-CdS (01-077-2306)
w-CdS (01-077-2306)
c-CdS (00-042-1411)
9
13 (blende)
8 (wurtzite)
19 (wurtzite)
11 (blende)
28±8
28.6
CdNEO
CdADE
480
400
35±9
16±4
25.7
25.0
42.7
22.2
[a] JPDS card number. [b] Mean particle size estimated from Debye-Scherrer equation. Diffraction peaks chosen for each crystalline phase: (111) for Pd,
(110) for w-ZnS, (110) for w-CdS and (200) for c-CdS. [c] Mean particle size along with its standard deviation calculated from the statistical analysis of
TEM images. [d] C.V.: coefficient of variation. [e] Carbon mass percentage calculated by thermogravimetry.
4
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10.1002/ejic.201701475
European Journal of Inorganic Chemistry
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Figure 4. X-ray diffraction patterns of dry thermolysis products obtained
under aerobic conditions at 345–480°C for 15 minutes.
SEM images were performed over combustion samples in order
to inquire into their microstructural characteristics (Figure 5).
Thermolysis products of PdBPY and PdPHEN consist of compact
microsized aggregates with smooth surfaces. At high
magnifications, the nanoparticles embedded in the carbon matrix
are hardly discerned, despite they will become clear in below
described TEM analysis. In the case of ZnNEO, the obtained
product shows greater compositional heterogeneities at nanometric
scale since ZnS nanoparticles tend to aggregate forming clusters of
approximately 1–3 micron. Thermolysis of CdBPE generates an
agglomerated granular nanotexture indicative of the presence of
partially sintered nanocrystallites. CdS/C nanocomposite prepared
from compound CdNEO presents a higher surface rugosity in
comparison to the product of ZnNEO (despite both precursors
contain neocuproine ligand). The dispersed CdS nanoparticles
exhibit a well-defined spherical shape and are better distributed
along the carbon matrix at nanoscale. Like carbon-rich precursors
(PdPHEN, ZnNEO and CdNEO), compound CdADE degrades
creating completely compact and glassy surfaces. However, the
compositional arrangement of the material is just the reverse:
carbon is grouped forming microparticles and these are surrounded
by a matrix composed of CdS nanoparticles linked to each other
through a thin carbon coating (Figure 6a-d). This unexpected
phenomenon will be discussed later when analyzing the TEM
images of samples.
Figure 5. SEM images (10 kX of magnification on the left and 100 kX
rightwards) of decomposition products synthetised from (a) PdBPY, (b)
PdPHEN, (c) ZnNEO, (d) CdBPE and (e) CdNEO after having been
subjected to 345–480°C for 15 minutes.
TEM was employed to get a better insight into the generated
nanocomposites (Figure 7). Transmission micrographs confirm the
existence of nanoparticles dispersed into an amorphous
carbonaceous matrix. Data on statistical particle size analysis of the
TEM images are provided in Table 2. Accordingly, elemental
palladium nanoparticles display a bimodal size distribution in
which fine particles (3–21 nm) (Figure 7a-b) and coarse particles
(>40 nm) (Figure S5.8) can be distinguished. With regard to
particle morphology, spherical particles and low aspect ratio
nanorods are obtained for PdBPY and PdPHEN, respectively. This
clue suggests that the heterocyclic co-ligand plays a key role in
both size and morphology of the resulting Pd nanoparticles.
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10.1002/ejic.201701475
European Journal of Inorganic Chemistry
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of them have monomodal curves except CdS nanoparticles
prepared from CdNEO which describe a bimodal behavior with
maxima around 25–30 nm and 35–40 nm. The effect of the metal
center on particle size also becomes evident by observing the size
distributions of sulfide obtained from ZnNEO and CdNEO; ZnS
obtained from ZnNEO is composed of nanoparticles lower than 15
nm whereas all CdS nanoparticles generated from CdNEO exceed
this limit.
TEM images taken on thermolysis product of CdADE will serve
to enlighten about the mechanism of formation of the
aforementioned micrometric carbon clusters (Figure 6). During dry
thermolysis, the first nucleation points appear at the surface of the
precursor grains and they grow by incorporating the further
cadmium and sulfur atoms that diffuse from inner core of the grain.
As semiconducting nanoparticles are formed, they tend to diffuse
towards grain boundaries and accumulate therein creating a species
of halos for greater carbonaceous agglomerates (Figure S5.9) but a
more homogeneous dispersion is obtained for smaller ones. When
the grain size is relatively small (< 1 μm) this phenomenon is not
observable because nanoparticles do not have enough space to
move and well dispersed agglomerates are generated.
Figure 6. SEM images at different magnifications obtained for thermolysis
product of compound CdADE (400ºC for 15 min).
On the contrary, the sizes found for metal sulfide nanoparticles
show smaller polydispersion (coefficients of variation less than
29 %) and generally, smaller than 60 nm (Figure 8). The resulting
sizes are comparable to those obtained by wet routes in which
surfactants are employed to control particle growth kinetics.[23] All
Figure 7. TEM images of thermolysis products: (a) PdBPY, (b) PdPHEN, (c) ZnNEO, (d) CdBPE, (e) CdNEO and (f) CdADE.
6
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Thus, the carbonaceous matrix in palladium products contains also
amorphous phase of sulfide or palladium sulfate which has not yet
been reduced to metal (note, that according to thermogravimetric
analysis PdSO4 precedes to the formation of elemental Pd). This
sulfur impurities together with the small particle size in PdBPY
and high carbon content in PdPHEN seems to hinder the
recognition of crystallographic planes.
Influence of thermal treatment parameters. In order to
understand the degree of influence of the main thermolysis
variables on the particle size, crystallinity and the final carbon
content of the product, different thermogravimetric tests were
performed on the precursor PdBPY. Despite particle size
polydispersion found in elemental Pd samples, Debye-Scherrer
analysis and TEM images allow to monitor how coarse and fine
particles evolve, respectively. When fixing the onset temperature at
345ºC, TEM images (Figure 9) show how finest particles tend to
grow progressively from 3–5 nm at five minutes of treatment time
to 80–200 nm after sixty minutes. Considering that the carbon
matrix prevents the particle sintering, its elimination as the
exposure time increases, prompts the nuclei growth by following
Ostwald's maturation but also their aggregation into bigger sized
cumuli (500–1000 nm). Accordingly, the flattening of PXRD
background (Figure S4.2) as the treatment time increases is also
consistent with the decrease of the amorphous carbon amount.
Similarly carbonaceous matrix is also reduced when increasing the
onset temperature (at fixed exposure time and heating rate; Figure
S4.3) and lowering heating rate (at fixed exposure time and onset
temperature; Figure S4.4). Again, Debye-Scherrer analysis (Table
3) does not allow to follow the evolution of finest particles, but it
indicates that after fifteen minutes the sintering of small particles
into coarse crystallites reaches a limit close to 60 nm. Regarding
influence of thermal treatment parameters on the formation of
metal sulfides, ZnNEO and CdNEO have been selected as
representaive cases. Unlike Pd particles, the size of ZnS and CdS
particles is not affected by the exposure temperature and time
within the analysed range (400–480ºC; < 60 min).
Figure 8. Particle size histograms estimated from TEM images acquired for
different decomposition products.
Table 3. Debye-Scherrer expression based crystallite size analysis of
cadmium and zinc based compounds.
On the other hand, decomposition products show a low degree of
agglomeration of nanoparticles within the carbon matrix, being
noticeable the individual morphology of themselves along the solid.
In MS/C samples, it has even been possible to identify certain
crystallographic orientations (Figure S5.10) in contrast to Pd/C
nanocomposites. The interplanar distances measured match those
expected for each decomposition product: 0.1977 nm for sample
ZnNEO which corresponds to the plane (110) of ZnS wurtzite
phase, 0.1743 nm for sample CdBPE which coincides with the
plane (331) of the CdS cubic phase, 0.2474 nm for sample CdNEO
which adjusts to (102) reflection of CdS wurtzite phase and 0.2086
nm for sample CdADE which is consistent with (220) index of CdS
cubic polymorph. Each decomposition product has been subjected
to qualitative compositional measurements using EDX analysis
(Figure S5.11). In zones with lower contrast (i.e. matrix rich zone)
the carbon ratio is substantially higher, being this increment more
abrupt in carbon rich products obtained from PdPHEN, ZnNEO,
CdNEO and CdADE. In the case of Pd/C nanocomposites, spectra
realized over these brighter areas also show an additional peak
corresponding to S element with a Pd/S ratio close to the unity.
Precursor T (ºC) [a] rH (ºC·min-1) [b]
t (min)
5
15
30
60
5
15
5
5
15
15
60
15
15
60
(hkl)
(111)
(111)
(111)
(111)
(111)
(111)
(111)
(111)
(110)-w
(110)-w
(110)-w
(110)-w
(110)-w
(110)-w
Dv (nm)
41
60
66
57
345
345
345
345
345
345
345
360
400
480
480
400
480
480
5
5
5
5
PdBPY
15
15
30
32
69
[c]
15
67
9
9
[d]
[d]
[d]
[d]
[d]
[d]
ZnNEO
CdNEO
8
15
19
17
[a] Combustion temperature. [b] Heating rate. [c] The crystallite size could
not be estimated due to the large background level exhibited that partially
obscures the diffraction peaks. [d] The precursor was introduced into a
preheated oven.
7
This article is protected by copyright. All rights reserved.

10.1002/ejic.201701475
European Journal of Inorganic Chemistry
FULL PAPER
Figure 9. TEM images of the products obtained from compound PdBPY at different combustion times: (a) 5 min, (b) 15 min, (c) 30 min, and (b) 60 min.
nanostructures does not require expensive equipment and
Conclusions
production times are brief. Furthermore, the possibility of working
under aerobic conditions reduces costs substantially. All these
reasons make dry thermolysis an interesting synthetic method in
order to satisfy the industrial demand of this class of materials.
We have obtained six different air-stable metal-thiobenzoato
compounds (M: Pd, Zn, Cd) containing N-heterocycles (bpy, phen,
neo, bpe and ade) to complete the coordination sphere of the
metal(II) atom. The presence of direct metal-sulfur bonds is a key
Experimental Section
factor to use these compounds as single-source precursors for the
synthesis of nanometric chalcogenide particles. Despite
thiocarboxylate based compounds are characterized by
experiencing complete decompositions at relatively low
temperatures,[24] the use of ligands containing aromatic rings make
feasible to afford through a mild thermolysis treatment in air
atmosphere carbon supported metal and metal sulfide
nanocrystallites. The nature of the starting metal-thiobenzoato
precursor seems to exert a crucial influence on the final blende or
wurtzite crystalline phase of the resulting metal(II) sulfide
nanoparticles, as neocuproine based compounds with π-extended
systems give rise to wurtzite phase, whereas less π-extended
adenine and 1,2-di-(4-pyridil)-ethylene provide blende phase and
mixture of both polymorphic phases, respectively. The carbon
content in each sample is also strongly influenced by the nature of
the co-ligand. Phen, neo and ade form non-volatile byproducts
during pyrolysis resulting in carbonaceous matrices, whereas less
fused ligands such as bpy and bpe practically generate pure
samples.
General information. Commercially available zinc acetate dihydrate
(Zn(OAc)2·2H2O), cadmium acetate dihydrate (Cd(OAc)2·2H2O),
palladium acetate (Pd(OAc)2), thiobenzoic acid (HTBn), 2,2’-bipyridine
(bpy), 1,10-phenanthroline (phen), neocuproine (neo), 1,2-di-(4-pyridil)-
ethylene (bpe), adenine (ade) and all the solvents were of analytical grade
and they were used without further purification. The new compounds are
stable in air at room temperature. Data on the solubility of the compounds
in common solvents is provided in the supporting information. The yields
calculated are based on metal salt.
[Pd(TBn)2(bpy)] (PdBPY): 2.5 mmol (0.561 g) of Pd(OAc)2 were
dissolved in 45 mL of N,N’-dimethylformamide (DMF). In another beaker,
2.5 mmol of bpy (0.390 g) and 5 mmol (430 μL)of HTBn were dissolved in
5 mL of DMF. The resulting solution was added over the solution
containing the metal salt while it was subjected to magnetic stirring. In few
seconds the dark reddish solution became opaque by the appearance of a
yellowish polycrystalline powder of PdBPY. One hour later the obtained
product was filtered and then washed several times with methanol (MeOH)
to finally be dried at room temperature for one day. The filtrate was left
undisturbed at room temperature to obtain yellow single crystals of PdBPY
suitable for X-ray diffraction analysis. Yield (based on metal salt): 0.8993 g
(67%). Main IR features of compound PdBPY ῡ(cm–1): 3163(vw), 3104(w),
3093(vw), 3078(w), 3058(w), 3029(vw), 2995(vw), 1671(w), 1609(vs),
1595(vs), 1573(s), 1491(w), 1483(w), 1464(w), 1441(s), 1415(w),
1387(vw), 1318(w), 1313(w), 1303(m), 1290(w), 1277(vw), 1263(vw),
1257(vw), 1245(w), 1201(s), 1175(m), 1119(vw), 1104(w), 1096(vw),
1080(w), 1066(w), 1044(vw), 1030(w), 1020(w), 1005(vw), 992(vw),
972(vw), 931(m), 907(s), 846(vw), 800(vw), 775(m), 763(s), 725(m),
702(m), 695(s), 660(m). Anal. Found (%): C, 53.79; H, 3.45; N, 5.42; Pd,
19.55; S, 11.88. Calc. for C24H18N2O2PdS2 (%): C, 53.68; H, 3.38; N, 5.22;
Pd, 19.82; S, 11.94.
Zn(II) and Cd(II) metal-organic precursors render metal(II)
sulfide nanoparticles with a fine size distributions and mean size
values ranging from 8 to 19 nm. On the contrary, Pd(II) complexes
lead to metal nanoparticles with a significant polydispersion, where
fine particles (3–20 nm) and coarser ones (< 40 nm) can be
distinguished. Accordingly, the analysis of thermal treatment
parameters shows that the formation of Pd nanoparticles is highly
sensitive to exposure time, heating rates and onset temperature, in
such a way that sintering and nuclei growth can be notably affected.
On the other hand, size of the formed metal(II) sulfide
nanoparticles is not notably influenced by aforementioned
parameters, which makes them more reliable product for a
hypothetic upscaling. Thus, the single-step method for obtaining
8
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10.1002/ejic.201701475
European Journal of Inorganic Chemistry
FULL PAPER
[Pd(TBn)2(phen)] (PdPHEN): The synthetic procedure was similar to that
of PdBPY, except that phen (2.5 mmol, 0.450 g) was used instead of bpy.
In this case ligands were added sequentially onto the solution containing the
dissolved metal salt (first HTBn and then phen). The polycrystalline
product of PdPHEN was washed with MeOH. The mother liquors were left
undisturbed at room temperature to obtain yellow single crystals. Yield:
1.1503 g (82%). Main IR features of compound PdPHEN ῡ(cm–1):
3158(vw), 3143(vw), 3067(w), 3024(w), 2992(w), 2926(vw), 2856(vw),
1674(m), 1608(vs), 1595(vs), 1570(vs), 1513(m), 1496(w), 1481(w),
1449(sh), 1444(m), 1421(s), 1413(w), 1403(w), 1387(w), 1338(m),
1318(w), 1309(w), 1290(w), 1253(vw), 1218(vw), 1193(s), 1167(s),
1143(w), 1106(m), 1093(w), 1076(w), 1056(vw), 1036(vw), 1024(vw),
1000(vw), 987(vw), 931(m), 908(vs), 875(w), 847(s), 813(vw), 797(vw),
776(s), 739(w), 723(vw), 718(s), 691(s).
another beaker, 2.5 mmol (0.338 g) of ade and 5 mmol (430 μL) of HTBn
were mixed in 8 mL of hot MeOH. Immediately, the mixture becomes clear
and after one hour of stirring at room temperature the yellow solution is
kept in a refrigerator at about 5 ºC. Several days after CdADE appeared as
colourless single-crystals mixed with a whitish polycrystalline powder.
Yield: 0.7614 g (55 %). Main IR features of compound CdADE ῡ(cm–1):
3240(m), 3154(m), 3053(s), 2963(m), 2814(m), 2714(w), 2668(w),
1678(vs), 1647(w), 1599(w), 1585(m), 1545(sh), 1524(s), 1512(s), 1445(s),
1427(m), 1414(m), 1337(m), 1308(w), 1230(sh), 1204(vs), 1167(s),
1119(w), 1101(w), 1076(w), 1059(sh), 1026(vw), 999(vw), 937(s), 916(s),
895(m), 843(w), 824(w), 775(m), 716(vw), 690(s), 656(w). Anal. Found
(%): C, 43.33; H, 3.49; Cd, 20.31; N, 12.67; S: 11.62. Calc. for
C20H19CdN5O3S2 (%): C, 43.36; H, 3.46; Cd, 20.29; N, 12.64; S, 11.58.
Physical measurements. Elemental analyses (C, H, N, S) were performed
on a Euro EA Elemental Analyzer, whereas the metal content was
determined by inductively coupled plasma (ICP-AES) using a Horiba
Yobin Yvon Activa spectrometer. Infrared spectra (ATR mode) were
Anal. Found (%): C, 55.58; H, 3.16; N, 5.04; Pd, 19.09; S, 11.37. Calc. for
C26H18N2O2PdS2 (%): C, 55.67; H, 3.23; N, 4.99; Pd, 18.97; S, 11.43.
[Zn(TBn)2(neo)] (ZnNEO): The procedure is similar to that of compound
PdBPY. Zn(OAc)2·2H2O (2.5 mmol, 0.545 g) was used instead of
Pd(OAc)2 and bpy was replaced by neo (2.5 mmol, 0.520 g). The solvent
selected for the reaction was MeOH. In few seconds the colorless solution
became opaque by the appearance of a whitish polycrystalline powder of
ZnNEO. One hour later the obtained product was filtered and then washed
several times with methanol (MeOH) to finally be dried at room
temperature for one day. The filtrate was left undisturbed at room
temperature to obtain colourless single crystals. Yield: 1.2052 g (88 %).
Main IR features of compound ZnNEO ῡ(cm–1): 3065(w), 3022(w),
1619(w), 1596(vs), 1567(vs), 1500(m), 1481(w), 1441(m), 1426(w),
1375(w), 1337(vw), 1325(vw), 1299(w), 1245(vw), 1220(w), 1194(vs),
1164(s), 1151(sh), 1130(sh), 1098(vw), 1071(vw), 1054(vw), 1026(w),
1001(vw), 987(vw), 970(vw), 920(vs), 853(m), 843(w), 813(vw), 791(sh),
781(sh), 774(m), 729(w), 691(s), 683(m), 663(vw). Anal. Found (%): C,
61.45; H, 3.92; N, 5.08; S, 11.75; Zn: 11.94. Calc. for C28H22N2O2S2Zn (%):
C, 61.37; H, 4.05; N, 5.11; S, 11.70; Zn, 11.93.
recorded at
a resolution of 4 a FTIR 8400S Shimadzu
cm-1 on
spectrophotometer for a total of 40 scans in the 4000–650 cm–1 spectral
region. Thermal analysis (TG/DTG/DTA) were carried out on a Mettler
Toledo TGA/SDTA 851e thermal analyser employing a synthetic air (79%
N2, 21% O2) flux of 150 cm3∙min-1 with heating rates of 5–30 ºC∙min-1 and a
sample size of about 10–25 mg per run. Combustions of precursors were
performed under aerobic conditions using a Carbolite 3216 tubular furnace.
The X-ray powder diffraction patterns (PXRD) were collected on a X-Pert
PRO PAN analytical machine employing a Cu Kα radiation source at a
scanning rate of 0.026°∙s–1. The average diameter of particles (Dv) has been
calculated from Dv = (4/3)∙Lv expression. LV = K∙λ/β∙cosθ, where LV is the
volume-weighted average crystallite size measured in
a direction
perpendicular to surface of the specimen, λ is the average wavelength, in
nanometers of the Kα radiation of Cu (0.154252 nm), θ is the Bragg angle
in radians, β (2θ) is the Full Width at Half Maximum (FWHM) of the
diffraction peak in radians discounting instrumental contribution
[FWHM(º) = 0.0755 + 4 x 10-4·2θ] and K is the shape factor constant,
considered as 0.9.
[Cd(TBn)2(μ-bpe)]n (CdBPE): The synthetic procedure was similar to that
of ZnNEO, except that Cd(OAc)2·2H2O (2.5 mmol, 0.670 g) was used as
metal source, bpe (2.5 mmol, 0.455 g) was used instead of neo and HTBn
was added firstly onto metal solution. After one hour of reaction a
yellowish powder of CdBPE was recovered. The filtrate was left
undisturbed at room temperature to obtain yellow single crystals. Yield:
1.1239 g (79 %). Main IR features of compound CdBPE ῡ(cm–1): 3068(vw),
3050(vw), 3024(vw), 1601(vs), 1555(s), 1537(s), 1501(m), 1483(w),
1445(w), 1426(s), 1351(w), 1304(w), 1259(vw), 1247(vw), 1204(vs),
1168(s), 1155(sh), 1115(vw), 1097(vw), 1068(m), 1019(w), 1011(m),
1001(w), 982(m), 961(w), 938(s), 923(s), 866(w), 845(sh), 833(s), 799(sh),
775(s), 742(vw), 721(vw), 689(vs), 675(sh), 652(w). Anal. Found (%): C,
54.92; H, 3.57; Cd, 19.70; N, 4.87; S, 11.21. Calc. for C26H20CdN2O2S2 (%):
C, 54.88; H, 3.54; Cd, 19.76; N, 4.92; S, 11.27.
The morphology of carbon supported nanoparticles was examined using a
JEOL JSM-7000F scanning electron microscope (SEM) and a Philips
CM200 transmission electron microscope (TEM) equipped with an EDXS
collection unit. The samples for SEM were prepared just by deposition of
the product on a carbon tape while those for TEM were dispersed on
ethanol solution containing 5 %wt of n-decylamine and placed on a carbon-
coated copper grid followed by drying under vacuum.
X-ray structure determination. Diffraction experiments were carried out
on an Agilent Technologies SuperNova diffractometers (λCu−Kα = 1.54184 Å
for PdBPY, PdPHEN and CdNEO; λMο−Kα = 0.71073 Å for ZnNEO, CdBPE
and CdADE). Data were processed and corrected for Lorentz and
polarization effects with the CrysAlisPro program.[25] The structures of all
compounds were solved by direct methods using the SIR92 program (Table
4 and 5).[26] Full matrix least-squares refinements were performed on F2
using SHELXL97.[27] All non-hydrogen atoms were refined anisotropically.
All calculations for these structures were performed using the WINGX
crystallographic software package.[28] During the data reduction process of
PdPHEN, CdNEO and CdADE, it became clear that the crystal specimens
were twinned with twin laws: (-0.9999 0.0002 -0.0000 / -0.0002 -1.0002 -
0.0002 / 0.3008 -0.0007 0.9996) for PdPHEN; (-1.0000 -0.0005 0.0001 /
0.0159 0.0828 -0.9106 / -0.0160 -1.0899 -0.0850) for CdNEO; (-0.4089
0.0003 -0.5927 / -0.0003 -1.0000 -0.0001 / -1.4040 0.0010 0.4094) for
CdADE. The final result showed a percentage for minor component of
45.9% (PdPHEN), 36.7% (CdNEO), 41.6% (CdADE). In compound
CdBPE, one of the crystallographically independent thiobenzoate ligands is
disordered over two almost coplanar arrangements with 50% occupation
[Cd(TBn)2(neo)] (CdNEO): The synthetic procedure was similar to that of
CdBPE, except that neo (2.5 mmol, 0.520 g) was used instead of bpe. The
polycrystalline product of CdNEO was washed with MeOH. The mother
liquors were left undisturbed at room temperature to obtain pale-yellow
single crystals. Yield: 1.3831 g (93 %). Main IR features of compound
CdNEO ῡ(cm–1): 3053(w), 3022(w), 2999(vw), 2966(vw), 2922(vw),
1616(w), 1590(m), 1539(s), 1502(s), 1441(m), 1410(w), 1376(w), 1364(w),
1305(w), 1291(w), 1251(vw), 1207(vs), 1172(m), 1152(m), 1118(sh),
1102(vw), 1075(w), 1025(w), 994(vw), 931(vs), 858(m), 844(w), 810(vw),
793(vw), 773(m), 728(w), 691(vs), 654(w). Anal. Found (%): C, 56.50; H,
3.62; Cd, 18.78; N, 4.80; S: 10.86. Calc. for C28H22CdN2O2S2 (%): C, 56.52;
H, 3.72; Cd, 18.89; N, 4.71; S, 10.79.
[Cd(TBn)2(ade)] (CdADE): 2.5 mmol (0.670 g) of Cd(OAc)2·2H2O was
dissolved in 40 mL of MeOH and allowed to stir at room temperature. In
9
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10.1002/ejic.201701475
European Journal of Inorganic Chemistry
FULL PAPER
factors. The internal carboxylate bond distances in the disordered
thiocarboxylate were imposed to be nearly equal using SADI command.
Table 4. Crystal data and structure refinement of the compounds PdBPY, PdPHEN and ZnNEO.
Compound
Empirical formula
Mr [g mol-1]
T [K]
PdBPY
C24H18N2O2PdS2
536.92
PdPHEN
C26H18N2O2PdS2
560.94
ZnNEO
C28H22N2O2S2Zn
547.96
100(2)
100(2)
293(2)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
monoclinic
C2/c (No.15)
23.9837(14)
9.4545(3)
9.8614(6)
90
monoclinic
I2/a (No.15)
10.1891(3)
10.4666(3)
20.3093(6)
90
Orthorhombic
Pbcn (No.60)
20.8924(6)
13.3194(6)
9.1806(3)
90
α [°]
β [°]
112.358(7)
90
2068.0(2)
4
1.725
9.335
94.328(3)
90
2159.71(11)
4
1.725
8.972
90
90
γ [°]
V [Å3]
2554.72(16)
4
1.425
Z
ρcalcd [g cm-3]
μ [mm-1]
1.153
F(000)
1080
1128
1128
θ range [°]
Reflections collected
Independent reflections
Parameters/restraints
R[I > 2σ(I)][a]
3.99–73.98
2074
2021
4.37–73.97
5464
5159
2.87–26.00
2508
1550
141/0
151/0
160/0
R1 = 0.0363
wR2 = 0.1015
R1 = 0.0370
wR2 = 0.1019
1.178
R1 = 0.0428
wR2 = 0.1190
R1 = 0.0443
wR2 = 0.1200
1.024
R1 = 0.0478
wR2 = 0.1164
R1 = 0.0802
wR2 = 0.1317
0.905
R (all data)
GOF on F2 (S)[b]
Weighting scheme[c]
SHELX
SHELX
SHELX
[a] R1 = Σ(|F0| – |Fc|)/Σ|F0|; wR2 = {Σ[w(F02 – Fc2)2]/Σ[w|F0|2]}1/2. [b] S = [Σw(|F0| – |Fc|)2/(Nobs – Nparam)]1/2. [c] Scheme = I/[σ2(F02) + (aP)2 + bP] where P =
(F02 + 2Fc2)/3; compound (a,b): PdBPY (0.0426, 16.6867), PdPHEN (0.1028, 0), and ZnNEO (0.0543, 0).
Table 5. Crystal data and structure refinement of the compounds CdBPE, CdNEO and CdADE.
Compound
Empirical formula
Mr [g mol-1]
T [K]
CdBPE
C26H20CdN2O2S2
568.96
CdNEO
C28H22CdN2O2S2
594.99
CdADE
C20H19CdN5O3S2
553.92
100(2)
100(2)
100(2)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
monoclinic
C2/c (No.15)
25.0653(5)
12.3273(2)
16.1337(3)
90
105.714(2)
90
4798.79(16)
8
triclinic
monoclinic
P21/n (No.14)
11.2499(5)
10.7383(5)
18.2771(7)
90
96.992(4)
90
2191.54(17)
4
P-1 (No.2)
9.0970(7)
11.1808(10)
12.4222(9)
81.599(7)
83.998(6)
85.110(7)
1239.93(17)
2
α [°]
β [°]
γ [°]
V [Å3]
Z
ρcalcd [g cm-3]
1.575
1.110
1.594
8.859
1.679
1.219
μ [mm-1]
F(000)
2288
600
1112
θ range [°]
Reflections collected
Independent reflections
Parameters/restraints
R[I > 2σ(I)][a]
1.69–28.30
5488
4917
3.61–74.00
8573
6970
2.02–28.35
8763
7085
289/5
317/0
286/0
R1 = 0.0425
wR2 = 0.1000
R1 = 0.0482
wR2 = 0.1044
1.039
R1 = 0.0476
wR2 = 0.1181
R1 = 0.0578
wR2 = 0.1214
0.959
R1 = 0.0285
wR2 = 0.0718
R1 = 0.0359
wR2 = 0.0733
0.975
R (all data)
GOF on F2 (S)[b]
Weighting scheme[c]
SHELX
SHELX
SHELX
[a] R1 = Σ(|F0| – |Fc|)/Σ|F0|; wR2 = {Σ[w(F02 – Fc2)2]/Σ[w|F0|2]}1/2. [b] S = [Σw(|F0| – |Fc|)2/(Nobs – Nparam)]1/2. [c] Scheme = I/[σ2(F02) + (aP)2 + bP] where P
= (F02 + 2Fc2)/3; compound (a,b): CdBPE (0.0390, 33.3626 ), CdNEO (0.0819, 0) and CdADE (0.0472, 0).
Supporting Information (see footnote on the first page of this article):
Thermoanalytic data, PXRD patterns, FTIR spectra, SEM/TEM images,
Acknowledgments
bond distances and angles, figures of crystal packings and thermolysis
optimization experiments. Crystallographic data for structures reported in
This work has been funded by Universidad del País Vasco/Euskal Herriko
this paper have been deposited in the Cambridge Crystallographic Data
Unibertsitatea (PPG17/37 and UFI 11/53) and Ministerio de Economía y
Center under reference numbers CCDC 1552445-1552450. These data can
be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif.
Competitividad (MAT2016-75883-C2-1-P). Technical and human support
10
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10.1002/ejic.201701475
European Journal of Inorganic Chemistry
FULL PAPER
provided by SGIker (UPV/EHU, MICINN, GV/EJ, ESF) is also
acknowledged.
Golberg, A. Yamada, H. Zhou, Energy Environ. Sci. 2014, 7, 1648–
1652.
[11] a) K. D. Collins, R. Honeker, S. Vázquez-Céspedes, D. -T. D. Tang,
F. Glorius, Chem. Sci. 2015, 6, 1816–1824; b) S. Hayashi, Y. Kojima,
T. Koizumi, Polym. Chem. 2015, 6, 881–885; c) F. -X. Felpin, T.
Ayad, S. Mitra, Eur. J. Org. Chem. 2006, 2679–2690; d) A. Perosa,
P. Tundo, M. Selva, S. Zinovyev, A. Testa, Org. Biomol. Chem.
2004, 2, 2249–2252; e) N. Nakamichi, Y. Kawashita, M. Hayashi,
Org. Lett. 2002, 4, 3955–3957.
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Dry-thermolsysis / Carbon supported
nanoparticles *
Daniel Vallejo-Sánchez, Garikoitz
Beobide,* Oscar Castillo,* Mónica
Lanchas, Antonio Luque, Sonia Pérez-
Yáñez, Pascual Román
Page No. – Page No.
Metal-thiobenzoato complexes:
synthesis, structure and processing
as carbon supported nanoparticles
Six new air-stable metal-thiobenzoato compounds with N-heterocycles have been
synthesized and structurally characterized. Their solventless thermolysis under
aerobic conditions and at relatively mild temperature (350–480ºC) provides in a
single step carbon supported metal and metal sulfide nanoparticles with high
crystallinity.
Submitted to the European Journal of Inorganic Chemistry
13
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